Electric time delay relay



Jan. 30, 1945. v KlNSMAN 2,368,477

ELECTRIC TIME DELAY RELAY Filed June 22, 1942 Inventor: Ear-13V.Kinsman,

bg J/W a Kiwi His Attorney.

Patented Jan. 30, 1945 2,368,477 ELEc'rmc TIME DELAY RELAY Earle V.Kinsman, Scotia, N. Y., assignor to General Electric Company, acorporation of New York Application June 22, 1942, Serial No. 447,924

7 Claims.

My invention relates to electric circuits and more particularly toelectric circuits for obtaining a time delay operation of electricapparatus.

Electric valve apparatus or electric discharge devices have foundrelatively wide application in those systems where it is desired toproduce a time delay operation, such as the closure or opening of anelectric circuit, a predetermined interval of time after the initiationof a circuit controlling operation such as the closure of a switch orequivalent apparatus. In accordance with the teachings of my inventiondescribed hereinafter, I provide a new and improved control systemwherein greater precision and accuracy of operation are obtained thanthat afforded by the prior art arrangements, and which aifords greaterflexibility in the establishment of the timing interval.

It is an object of my invention to provide a new and improved electriccontrol circuit.

It is another object of my invention to provide a new and improvedelectric valve control circuit.

It is a further object of my invention to provide a new and improvedelectric valve time delay circuit whereby alternating current istransmitted to the energizing means of circuit controlling apparatus apredetermined interval of time after operation of a circuit controllingmeans.

Briefly stated, in the illustrated embodiment of my invention I providea new and improved electric valve time delay relay'whereby alternatingcurrent is transmitted to an actuating coil of a contactor or relay apredetermined interval of time after the initiation of a circuitcontrolling operation, such as the closure of a switch.

A pair of reversely connected electric discharge devices are connectedto the actuating coil of the relay. One of the discharge devices isnormally maintained non-conducting by virtue of a control circuitconnected to the grid of the discharge device and which is chargedthrough the grid-cathode circuit thereof through a circuit comprising acapacitance and a voltage divider which are energized from analternating current supply circuit. The other discharge device isnormally maintained non-conducting and is controlled to conduct currentonly during those half cycles immediately succeeding half cycles ofconduction by the first electric discharge device. The second electricdischarge device is maintained non-conducting by impressing on its grida negative or hold-oif voltage produced by a polarity responsive circuitwhich comprises a circuit, I provide an electric discharge devicecapacitance and a properly poled unidirectional conducting device.

For a better understanding of my invention, reference may be had to thefollowing descrip tion taken in connection with the accompanyingdrawing, and its scope will be pointed out in the appended claims. Thesingle figure of the accompanying drawing diagrammatically illus tratesan embodiment of my invention as applied to a time delay system forefiecting energization of the actuating core of a relay.

Referring now to the single figure of the drawing, I have thereillustrated my invention as applied to a system for controllingthe'energiza tion of an electric circuit l by means of apparatusincluding an electric discharge device 2. The electric dischargedevice'2 is preferably of the type employing an ionizable medium, suchas a gas or a vapor, and comprises an anode 3, a cathode 4 and a controlmeans such as a control grid 5. If desired, the discharge device 2 mayhave an additional control means such as a shield grid 6 which isconnected to the oathode If desired, the electric discharge device 2 maycontrol the energization of the electric circuit I through'a contactormeans or a relay 1 having an actuating coil 8 and contacts il. Theelectric circuit l is closed or energized when the contacts 9 areclosed, and this operation is effected when the electric dischargedevice 2- conducts current.

In order to control the conductivity of the electric discharge device 2by controlling the potential of grid 5, I provide means energized froman alternating current circuit comprising conductors l6 and II. Thismeans may include a voltage divider comprising serially connectedresistances l2, l3andl4 which may be adjustable. I provide time delaymeans, such as a capacitance l5, for controlling potential of grid 5 torender the electric device 2 conducting a predetermined interval of timeafter the initiation of a circuit controlling operation. The capacitanceI5 is connected between grid 5 and an adjustable contact l6 ofresistance I3. I provide a discharge path ncluding a resistance llconnected across capacitance l5. Shield grid 6 and cathode 4 may beconnected to conductor ll through a resistance I8 and a filteringcapacitance l9 may be con-v nected between the cathode 4 and grid 6.

As a means for energizing the actuating coil 8 of relay 1 so thatalternating current is transmitted to this coil from the alternatingcurrent 28, also preferably of the type employing an ionizable mediumsuch as a gas or a vapor, and comprising an anode 2i, a cathode 22, acontrol grid 23, and may include a' shield grid 24 which is connected tothe cathode 22. The electric discharge device 28 is poled in oppositionto the electric discharge device 2 so that these devices conduct currentduring half cycles of voltage of opposite polarity.

I provide means in the time delay system for maintaining the electricdischarge device 20 non-conducting except during those intervals or hallcycles immediately following half cycles of conduction by electricdischarge device 2. This means comprises means responsive to theconductivity of the electric discharge device 2, or means responsive tothe voltage appearing across the anode and cathode olelectric dischargedevice 2. For example, I provide a polarity and Voltage responsivecircuit comprising a capacitance 25, which is charged through a circuitincluding a unidirectional conducting device 28, and which normallyimpresses a negative or hold-oii voltage on grid 23. If desired, thiscircuit may be connected to the alternating current circuit includingconductors l and Ilthrough a current limiting resistance 21 andactuating coil 8 of relay means I. The time constant of the dischargecircuit for capacitance 25 including the resistance29 determines therate or change of the bias voltage for discharge device 26. A suitablefiltering means, such as a capacitance 28, may be connected between thecontrol grid and cathode of electric discharge device 20.

I provide circuit controlling means, such as a switch 39, which may beconnected in the anodecathode circuits or electric discharge devices 2and 29 and which, when in the open circuit position, permits charging ofcapacitance [5 to impress a negative hold-off timing voltage on grid 5of electric discharge device 2 and, when in the closed circuit position,permits discharging or the capacitance l5, thereby decreasing themagnitude or the biasing potential and rendering electric dischargedevice 2 conducting a predetermined interval of time after closure.

Th operation or the time delay relay shown in the single figure 01' thedrawing will now be explained. So long as the switch 30 is maintained inthe open circuit position, the actuating coil 8 of relay "1 is notenergized. Of course, under these conditions neither electric dischargedevice 2 nor electric discharge device 20 conducts current through itsanode-cathode circuit. By virtue of the grid rectificationcharacteristic of the electric discharge device 2, the lower plate ofcapacitance I5 is charged negatively thereby producing initially thedesired negative timing voltage. The circuit through which thecapacitance I5 is charged to the polarity indicated during those halfcycles when the conductor ID is positive in potential relative toconductor II, is resistance 12, the left-hand portion of resistance I3,capacitance l5, control grid 5, cathode 4 and resistance l8.

Upon closure of switch 30, voltage is applied to the anode-cathodecircuits of the electric discharge devices 2 and 20. The voltage appliedto grid 5 of electric discharge device 2 then consists of twocomponents; one of these components is the alternating voltage derivedfrom the voltage divider, particularly contact N5 of resistance 13 andthe conductor ill; the second component is a unidirectional voltageappearing across capacitance l5. The alternating component of voltagetends to render the potential of control grid 5 positive when the anodeis positive but is rendered inefiective for a predetermined interval oftime dependent upon the time constant of the discharge circuit forcapacitance l5. Initially, the magnitude of this biasing potential ismaximum and substantially full line voltage appears between theconductor l0 and the anod of discharge device 2. Under these conditions,a unidirectional voltage is produced across discharge resistance 29 insuch a direction and having a polarity, due to the unidirectionalconducting device 20, to maintain the grid 23 of discharge device 20negative. Capacitance 25 is fully recharged during each positive halfcycle of applied anode-cathode voltage that the electric dischargedevice 2 does not conduct current. In this manner, the electricdischarge device 20 is also maintained in a noncdnducting state.

The charge on capacitance I5 is dissipated through resistance l'l,thereby causing the volt age applied to grid 5 to rise exponentially,that is, the negative bias voltage decreases at a rate determined by thetime constant of that circuit. After a predetermined interval of timedependent upon the values of capacitance l5 and resistance I1 and thesetting of contact It, the grid voltage of electric discharge device 2will become substantially zero and the electric discharge device 2 willbecome conductive during positive half cycles of applied anode-cathodevoltage, thereby energizing actuating coil 8 of relay 1. As soon aselectric discharge device 2 conducts current, the voltage appearingacross the anode and cathode thereof, and hence the voltage applied tothe charging circuit for capacitance 25, decreases to a small value.Consequently, capacitance 25 is not recharged and because of the lowtime constant of the discharge circuit for capacitance 25, the gridvoltage of discharge device 20 decreases to a value sufliciently smallto permit this valve to conduct current during each half cycleimmediately following the half cycles of conduction by electricdischarge device 2. Therefore, since discharge devices 2 and 20 conductalternately, alternating current is supplied to the actuating coil 8 ofrelay 7. The system may be reset in its operation by opening switch 30,which circuit controlling operation reestablishes the bias on the gridsof discharge devices 2 and 20.

An important advantage of my invention is the incident increasedaccuracy of the timing operation. This is due in a large measure to theuse of tWo electric discharge devices which insure that an even numberof half cycles of current will be supplied to the relay coil. Thisimproved accuracy is particularly apparent Where the time delay relay isemployed to provide short timing intervals. For example, the advantageof this timing means is particularly apparent in those applications,such as welding controls,- where accurate timing of welding operationsis desired.

Another advantage of my electric time delay relay is that a standardtype alternating current relay may be used in a normal manner in thesystem without requiring the use of additional current limiting means toprevent overload or overheating of the actuating coil of the relay.Furthermore, when two electric discharge devices are employed, thecurrent in each discharge device is less than in a single valve system.Con- While I have shown and described my inven-- tion as applied to aparticular system or connections and as embodying various devicesdiagrammatically shown, it will be obvious to those skilled in the artthat changes and modiflcations may be made without departing from myinvention, and I therefore aim in the appended claims to cover all suchchanges and modifications as fall within the true spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A time delay relay comprising a source of alternating voltage, anelectric discharge device having an anode. a cathode and a grid andconnected to be energized from said source, means comprising acapacitance energized from. said source for impressing on said grid ahold-off potential, 9. load circuit, a contactor mechanism havingcontacts connected in series relation with said load circuit and havingan actuating coil which is energized in series relation with theanode-cathode circuit of said discharge device,

a second electric discharge device connectedacross the anode and cathodeof the first-mentioneddischarge device and being poled in oppositionthereto, means responsive to the conductivity of vice for controllingthe conductivity of said second discharge device, and a switch connectedin series relation with said actuating coil across said source forcontrolling the charge of said capacitance.

2. In combination, cuit, an electric circuit, means for controlling theenergization of said 2 electric circuit comprising an electric dischargedevice having an anode,

a cathode and a grid, means comprising a capacitance connected to saidalternating current circuit for impressing a bias voltage on said gridtending to maintain said discharge device nonconducting, a relay havinga contact in said electric circuit and an operating coil connected inthe anode-cathode circui of said electric discharge device, a secondelectric discharge device having a grid and being connected across theanode and cathode of the first-mentioned discharge device and poled inopposition thereto, means for impressing on the grid of the seconddischarge device a voltage for controlling the conductivity thereof inresponse to the conductivity of the first-mentioned discharge device,and circuit controlling means for controlling said capacitance and forrendering the first-mentioned discharge device conducting apredetermined interval of time after operation thereof to operate thecontact in said electric circuit with a time delay. I

3. A time delay relay comprising a source of alternating voltage, anelectric discharge device having an anode, a cathode and a grid, meansenergized from said source and comprising a capacitance for impressingon said grid a negative biasing potential tending to maintain saiddischarge device non-conducting, a load circuit,

a contactor mechanism having contacts connected in series relation withsaid load circuit and having an actuating coil connected in seriesrelation with the anode-cathode circuit of said discharge device, asecond electric discharge device connected across the first-mentioneddischarge device and beink poled in opthe first-mentioned discharge deanalternating current cirpofltion thereto and having a grid, meansenergized from said source for impressing a holdor: volts-8Q on the gridof said second discharge deviceand responsive to the conductivity of thefirst-mentioned discharge device, and a switch connected in seriesrelation with said actuating coil across said source and being arrangedto 'efiect charge of said capacitance through the grid-cathode circuitwhen in the open circuit position and to effect discharge of saidcapacitance when in the closed circuit position to render said electricdischarge devices conduct inga predetermined interval of time after theclosure thereoi'.

4. In combination, an alternating currentcircuit, a madmmmt, and timedelay means for controlling the energization .of said load circuitcomprising an electric discharge device having an anode, acathode and acontrol grid, means for controlling the potential of said control gridincluding a voltage divider connected across said alternating currentcircuit and a capacitance connected between a point of said voltagedivider and said grid, a second electric discharge device connectedacross the anode and cathode of the first-mentioned discharge device andbeing poled in opposition thereto, means for controlling the potentialof the grid of said second discharge device in response to the magnitudeof the voltage appearing across the anode and cathode of saidfirst-mentioned discharge device during half cycles of voltage ofpredetermined polarity comprising a capacitance and a unidirectionalconducting device so that said second discharge device conducts currentduring only those positive half cycles of applied voltage immediatelysucceeding half cycles of conduction of the first-mentioned dischargedevice, a relay having a contact controlling the energization of saidload circuit and an operating coil connected in circuit with theanodecathode circuits of said electric discharge devices, and circuitcontrolling means connected to the first-mentioned discharge device forcontrolling the charging and discharging operations of thefirst-mentioned capacitance to control this energization of theoperating coil of said re ay.

5. In combination, an alternating current circuit, a load circuit, meansfor controlling the energization of said load circuit comprising anelectric discharge device having an anode, a cathode and a control grid,means energized from said al temating current circuit for controllingthe potential of said grid and comprising a voltage divider and acapacitance connected to said grid, a

mentioned discharge device and including a grid,

a second capacitance connected to the grid of said second dischargedevice, polarity responsive means for charging said second capacitancein response to the voltage appearing across said first-mentioneddischarge device, and switching means connected in circuit with theanode-cathode circuit of said first-mentioned discharge device forcontrolling the charging and discharging operations of thefirst-mentioned capacitance.

6. In combination, an alternating current circuit, an electric circuit,means for controlling the energization of said electric circuit andcomprising an electric discharge device having an anode, a cathode and agrid, means for controlling the potential of said grid comprising avoltage divider connected across said alternating current circuit and acapacitance connected between a point of said voltage divider and saidgrid, a second electric discharge device connected. across the anode andcathode of the first mentioned discharge device and poled in oppositionthereto, said second discharge 'device having a grid, means forimpressing on the grid of said second discharge device a voltage tendingto maintain said second discharge device normally non-conducting andtoincrease the potential of the grid in a positive direction in responseto conduction by the firstmentioned discharge device, a relay having acontact connected to control said electric circuit and an operating coilconnected in circuit with the anode-cathode circuits of said\ electricdischarge devices, and a switch connected to the first-mentioneddischarge device to eiiect charge 'of said capacitance when in the opencircuit position to maintain said discharge device non-conducting and toinitiate discharge of said capacitance when in the closed circuitposition thereby renderlng the first-mentioned discharge deviceconducting a predetermined interval of time after the closure thereof toeilect energization of the operating coil of said relay with a timedelay.

7. In combination, an alternating current ci-rcuit, a relay mechanismcomprising an actuating coil and contacts, an electric circuit connectedmean? to said contacts, and means for transmitting alternating currentto said actuating coll a predetermined interval of time after apredetermined circuit controlling operation and comprising an electricdischarge device having an mode, a cathode and a control grid, means forcontrolling the potential of said grid comprising a voltage dividerconnected across said alternating current circuit and a capacitanceconnected between a point of said voltage divider and said control grid,a second electric discharge device connected across the anode andcathode of the first-mentioned discharge device and being poled inopposition thereto, means for controlling the potential of the grid ofsaid seconddischarge device comprising a circuit responsive to thevoltage appearing between said anode and said cathode and including asecond capacitance and a unidirectional conducting device for chargingsaid second capacitance during the positive half cycles 01 voltageapplied to said'anode and said cathode, and circuit controlling meanscomprising a switch connected to the first-mentioned discharge devicefor controlling the charging and discharging operations of thefirst-mentioned capacitance and for controlling the potential of thefirst-mew tioned grid.

EARLE V. KINSMAN.

